1. Field of the Invention
The present invention relates to a burst phase detection circuit, in particular, relates to a burst phase detection circuit suitable for burst lock loop of a color video signal.
2. Description of the Prior Art
Color video signals contain a color signal where a carrier is modulated with first and second color difference signals. To digitally demodulate this color signal, the phase of a sampling clock for demodulating a particular color should be in synchronization with that of a color burst signal being input. If the phase of the sampling clock is not in synchronization with that of the color burst signal, the sampling value, that is, the demodulation output contains an error. Thus, the color cannot be correctly reproduced. With a conventional technique for controlling the phase of a sampling clock, data of the color burst signal being digitized is converted into an analog DC value by means of a D/A converter. Thereafter, the burst lock loop is controlled in accordance with the DC value.
The above mentioned prior art disadvantageously requires a D/A converter and the various associated circuit blocks for controlling the phase synchronization in accordance with the color burst signal of the sampling clock. Since it is difficult to include the D/A converter and the associated circuit blocks along with the circuit blocks for the phase control function of the sampling clock in an IC chip, the D/A converter and the associated circuit blocks should be externally provided.